Conventionally, motorcycles (or other types of vehicles) provided with an engine (internal combustion engine) including a coolant pump (pump part) are known. For example, Japanese Patent Document JP-B-3820970 discloses a lubricant cooling structure for an engine including: an oil pump drive gear (first gear) and a primary drive gear (second gear) that rotate together with a crankshaft; an oil pump idler gear meshed with the oil pump drive gear to rotate as the oil pump drive gear rotates; and a coolant pump gear (pump gear) meshed with the primary drive gear to rotate as the primary drive gear rotates. In this engine, the oil pump idler gear and the coolant pump gear are disposed inside a crankcase so as not to overlap each other as viewed from the extending direction of the crankshaft (from a side).
However, for this engine, because the oil pump idler gear and the coolant pump gear (pump gear) are disposed inside the crankcase so as not to overlap each other as viewed from the extending direction of the crankshaft (from a side), it is necessary to secure a space to be occupied by the oil pump idler gear and the coolant pump gear, which are respectively meshed with the oil pump drive gear (first gear) and the primary drive gear (second gear) which rotate together with the crankshaft inside the crankcase, in the direction perpendicular to the extending direction of the crankshaft. Therefore, the size of the engine (internal combustion engine) is increased in the direction perpendicular to the extending direction of the crankshaft. That is, the size of the internal combustion engine is increased as viewed from an end of the crankshaft.